I imagine some time of those 10.000 years will be suffering, some of it piecing together new memories but it will also give chance for great introspection. Phos has had over 300 years of timeskips with no chance to reflect upon stuff that was happening around them. It was pure chaos since the day they decided to travel to the ocean, seemingly making mistake after mistake with every step they took. For very static beings Phos the Mineral has undergone so much change so quickly that it is no wonder they lost their marbles.